Sidestream Treatment Processes Research Articles

Benchmarking sidestream shortcut nitrogen removal processes against nitrous oxide recovery from a life cycle perspective

Anaerobic digestion effluent adds significantly to nutrient loading, energy consumption, and emissions of wastewater treatment plants. Sustainably treating this ammonia-rich sidestream requires systematic analysis on environmental impacts of shortcut nitrogen removal processes. Coupled Aerobic–Anoxic Nitrous Decomposition Operation (CANDO) is a novel biotechnology for sidestream nitrogen removal with energy recovery potential from N2O. Nevertheless, the environmental impacts of CANDO remain unknown after initial scale-up studies. In this study, three sidestream treatment processes, namely, nitritation-denitritation, nitritation-anammox, and CANDO, integrated with mainstream anaerobic-anoxic-oxic (A2O) treatment routes, are assessed by process simulation and life cycle assessment (LCA). The results show that the nitritation-anammox process has the smallest effect on human health, ecosystem quality, and resource availability among the three routes. Furthermore, the global warming potential generated from the CANDO-A2O process is 157 kg CO2 eq per cubic meter of anaerobic digestion liquid treated, which is slightly higher than nitritation-anammox-A2O (132 kg CO2 eq) but remarkably lower than nitritation-denitritation-A2O (248 kg CO2 eq). With low carbon emission and promising alternatives for carbon source, the CANDO-A2O route exhibits great potential in achieving carbon neutrality. This work is the first to quantitatively evaluate the potential environmental impacts of CANDO from a life cycle perspective, providing insights on the adoption and optimization of shortcut nitrogen removal processes in sidestream treatment.

Expanding ASM models towards integrated processes for short-cut nitrogen removal and bioplastic recovery

In next-generation water resource recovery facilities (WRRFs), it is becoming increasingly important to save energy costs and promote resource recovery of valuable products. One way of reducing the substantial aeration energy costs at WRRFs is to employ shortcut N removal, while polyhydroxyalkanoate (PHA) production and recovery as bioplastic is a promising means of recovering a valuable product from biosolids. Both objectives can be achieved simultaneously through the Short-Cut Enhanced Phosphorus and PHA Recovery (SCEPPHAR) process. However, current mathematical models have not previously been employed to describe the behavior of such a process, which limits engineering design and optimisation of process operation. This work focusses on extending the ASM3 model towards the description of short-cut nitrogen removal and simultaneous PHA recovery in a sidestream treatment process. The calibrated and validated model described very well the nitritation process coupled with the aerobic feast/anoxic famine process for the selection of PHA producing organisms at a pilot-scale facility operated in Carbonera, Italy, where the normalised root mean squared error (NRMSE) was consistently <20%. Furthermore, the model applied to the PHA selection stage could effectively describe the PHA accumulation stage without recalibration. A simulation study was performed using the modified ASM3 model to assess the relative benefits of the SCEPPHAR process strategy as compared to the fully aerobic selection process for mixed culture PHA production. While the level of PHA production was found to be 34% lower with SCEPPHAR, a 43% savings in volatile fatty acids (VFAs) demand, a 15% decrease in Total suspended solids (TSS) production and a 28% decrease in oxygen demand were also achievable, which could lead to savings in operational costs. This study facilitates the design and optimisation of WRRFs that integrate short-cut N removal with PHA production, saving aeration energy costs while achieving resource recovery.

The impact of sludge return liquors on South African wastewater treatment plants

There have been three considerable shifts, in the past 20 years, in the conventional design and modelling of wastewater treatment plants (WWTPs): (i) single unit process to plant-wide modelling, (ii) consideration of WWTPs as water and resource recovery facilities (WRRFs), and (iii) the need to simplify WWTP models to allow their intake by new stakeholders (i.e. plant operators, designers and decision-makers) who use these models for evaluation of WWTP optimisation strategies. The latter shift has prompted the debate about model complexity versus the required modelling purpose among modellers. In addition to the aforementioned shifts, there has been limited research on the impact of sludge recycling dewatering liquor on the overall plant performance, especially in the context of South African WWTPs. A simplified full-scale steady-state WWTP simulation tool was developed, based on principles of sound mass-balance stoichiometry and rate-limiting kinetics. This tool enables the user to analyse the impact of recycling the DWL on the plant performance through different scenarios. The strategic scenarios evaluated included the implementation of two side-stream treatment processes (STPs), namely BABE and struvite precipitation. The evaluation of various strategies was done using the benchmark simulation model (BSM) task group plant performance indices (i.e. effluent quality and operational cost indices, EQI and OCI, respectively) incorporated into the simplified steady-state full-scale models. The integration of STP in the WWTP layout results in better EQI and OCI. The composition of the DWL affects the choice of the STP to be used, i.e., for DWL from an AD treating WAS that is not P-rich the recommended side-stream treatment operation would be the BABE process rather than struvite precipitation.

Ammonium recovery from process water of digested sludge dewatering by membrane contactors

Abstract Membrane contactors are a promising alternative for nitrogen removal and recovery from process water compared to other physicochemical and biological sidestream treatment processes. Münster wastewater treatment plant (WWTP) is the first municipal WWTP in Germany operating a full-scale membrane contactor system to improve the nitrogen elimination and recovery efficiency. Factors influencing the operation and membrane performance are investigated in an accompanying research project. Additional operational aspects of the applied membrane modules are investigated in detail using a bench-scale membrane contactor. First results of the full-scale application demonstrate a high nitrogen removal efficiency of &amp;gt;95%.

Sludge settling characterization for the mathematical modelling of sidestream treatment processes

More stringent effluent limits, especially with regard to total nitrogen, force wastewater treatment plants to consider sidestream nitrogen removal from digested sludge dewatering liquor which can contain up to 20% of incoming nitrogen load. Deammonification, the most promising biological technology for sidestream nitrogen removal, is based on partial short-cut nitrification and the Anammox process. Both steps of this process are conducted by slowly growing autotrophic bacteria, namely nitrifies and Anammox, which however may form different types of sludge: flocculent and granular, respectively. Nevertheless, ensuring effective sludge separation from treated effluent is crucial for the ability to retain both kinds of slowly growing biomass in the system. This paper presents the principles of sludge settling modelling, the results of a series of column tests conducted on sludge from pilot-scale two-stage deammonification treatment facility, as well as an attempt to estimate settling parameters in order to fit a sedimentation model.

Biodegradation and chemical precipitation of dissolved nutrients in anaerobically digested sludge dewatering centrate

The objective of this research was to assess specific side-stream treatment processes for biodegradation and precipitation of dissolved nutrients in dewatering centrate. In this study, characterization was made of a conventional suspended growth deammonification treatment process for transforming dissolved polyphosphate (poly-P), dissolved organic phosphorus (DOP) and dissolved organic nitrogen (DON) in two types of dewatering centrate. The deammonification process was configured as a sequencing batch reactor (SBR), combining partial nitrification and anaerobic ammonia oxidation (anammox) in a single tank. The first centrate feed studied was from the full-scale Annacis Island wastewater treatment plant (AIWWTP) located in Metro Vancouver, Canada. The second centrate feed was from a lab-scale anaerobic digester (AD) fed waste sludge from the existing City of Kelowna Wastewater Treatment Facility (KWTF), located in the Okanagan Valley, Canada. In addition, poly aluminum chloride (PACL) dosing was assessed for final polishing of dissolved nutrients. The deammonification SBR (DeSBR) process showed similar treatment characteristics for both the KWTF and AIWWTP centrates with excellent DON removal and poor non-reactive dissolved phosphorus (NRDP) removal. A statistical comparison of the DOP and poly-P through the DeSBR process suggests that DOP has a higher biodegradation potential. Future research focused on understanding the variables associated with degradation of DOP could lead to better NRDP removal through deammonification processes. Utilization of a post-anammox PACL chemical dosing stage can achieve the objective of precipitating any residual DON and NRDP and producing an effluent that has lower dissolved nutrients than the pre-digestion KWTF dewatering centrate scenario.

Technologies for Sidestream Nitrogen Removal

Liquid streams (known as “reject water” or “sidestream”) generated by the dewatering of digested solids generally contain high levels of ammonia and phosphorus. These liquids can be treated in separate or sidestream processes rather than being directly returned to the mainstream treatment process. Sidestream treatment processes can reduce overall energy and chemical costs and improve treatment reliability for biological nutrient removal facilities. Sidestream treatment processes can also be used for nutrient recovery and reuse. This document is a compilation of a broad range of biological and physiochemical treatment processes specifically for nitrogen removal and recovery from municipal sidestreams and ammonia-rich industrial wastewaters. The benefits of these technologies are described along with design approaches and full-scale plant experiences. Reuse of recovered ammonia in the form of aqueous ammonia and ammonium salts for industrial and agricultural applications is also discussed. Future research needs in sidestream nitrogen removal and recovery are identified and summarized. This title belongs to WERF Research Report Series ISBN: 9781780407890 (eBook)

Pilot-Scale Evaluation of pH-Based Control for Sidestream Treatment Processes

Pilot-Scale Evaluation of pH-Based Control for Sidestream Treatment Processes

Triple Bottom Line Evaluation of Biosolids Management Options

The overall goal of this energy project was to aid water resource recovery facilities (WRRF) in moving toward “net-zero” energy use through near-at-hand practices and technologies in the areas of energy conservation, demand reduction, and enhanced production. Many WRRFs looking to become Utilities of the Future are using Triple Bottom Line (TBL) assessments to inform decisions about opportunities for long term sustainability, and to evaluate common wastewater solids management technologies and processes amenable for energy recovery based on social and environmental impacts, as well as financial metrics. Funded through a collaborative effort between the New York State Energy Research and Development Authority (NYSERDA) and the Water Environment Research Foundation (WERF), researchers used a TBL approach to evaluate common wastewater solids management technologies and processes relative to their potential for long-term sustainability, including energy neutrality. The TBL assessment began at the point where solids are removed from wastewater (in primary and secondary clarifiers) and continued through the end use, or disposal, of the final product(s). To the extent practicable, the assessment included anaerobic digester sidestream treatment processes. This title belongs to WERF Research Report Series ISBN: 9781780407173 (eBook)

Techno-economic Assessment to Retrofit a Large Scale Deammonification Sidestream Treatment Process

Techno-economic Assessment to Retrofit a Large Scale Deammonification Sidestream Treatment Process

The Fate of Recalcitrant Nutrients Through an Anaerobic Digester and Anammox Sidestream Treatment Process

The Fate of Recalcitrant Nutrients Through an Anaerobic Digester and Anammox Sidestream Treatment Process

Designing to a Non-Defined Nutrient Regulation - Business Case Evaluation Applied to Mainstream and Side Stream Treatment Process Selection

Designing to a Non-Defined Nutrient Regulation - Business Case Evaluation Applied to Mainstream and Side Stream Treatment Process Selection

A distillery by-product as an external carbon source for enhancing denitrification in mainstream and sidestream treatment processes

The use of fusel oil as an 'alternative' carbon source for denitrification in the mainstream and sidestream treatment processes was studied. Research comprised two kinds of batch experiments as well as acclimation of process biomass to external carbon sources. In the conventional nitrate utilization rate (NUR) measurements (one-phase experiments with non-acclimated biomass), the NUR with fusel oil was 1.4-1.7 g N/(kg VSS·h which was comparable to NUR with ethanol and with slowly biodegradable fraction of the settled wastewater. When fusel oil was added at the beginning of the anoxic phase, preceded by an anaerobic phase (in two-phase experiments with non-acclimated biomass), the NURs of 2.5-2.9 g N/(kg VSS·h) were comparable to the tests without the addition of any external carbon sources. The addition of fusel oil and ethanol resulted in a significant enhancement of the denitrification efficiency in lab-scale sequencing batch reactors treating sludge reject water. The NURs continuously increased from below 1 g N/(kg VSS·h) to over 10 g N/(kg VSS·h) over the entire 4-week operational period, indicating gradual acclimation to the substrate. The overall total N removal efficiency reached ∼90%.

A Distillery By-Product as an External Carbon Source for Enhancing Denitrification in Mainstream and Sidestream Treatment Processes

The use of fusel oil as an ‘alternative’ carbon source for denitrification in the mainstream and sidestream treatment processes was studied. Research comprised two kinds of batch experiments as well as acclimation of process biomass to external carbon sources. In the conventional nitrate utilization rate (NUR) measurements (one-phase experiments with non-acclimated biomass), the NUR with fusel oil was 1.4–1.7 g N/(kg VSS·h which was comparable to NUR with ethanol and with slowly biodegradable fraction of the settled wastewater. When fusel oil was added at the beginning of the anoxic phase, preceded by an anaerobic phase (in two-phase experiments with non-acclimated biomass), the NURs of 2.5–2.9 g N/(kg VSS·h) were comparable to the tests without the addition of any external carbon sources. The addition of fusel oil and ethanol resulted in a significant enhancement of the denitrification efficiency in lab-scale sequencing batch reactors treating sludge reject water. The NURs continuously increased from below 1 g N/(kg VSS·h) to over 10 g N/(kg VSS·h) over the entire 4-week operational period, indicating gradual acclimation to the substrate. The overall total N removal efficiency reached ∼90%.

Effect of antiscalants on precipitation of an RO concentrate: Metals precipitated and particle characteristics for several water compositions

Inland brackish water reverse osmosis (RO) is economically and technically limited by the large volume of salty waste (concentrate) produced. The use of a controlled precipitation step, followed by solid/liquid separation (filtration), has emerged as a promising side-stream treatment process to treat reverse osmosis concentrate and increase overall system recovery. The addition of antiscalants to the RO feed prevents precipitation within the membrane system but might have a deleterious effect on a concentrate treatment process that uses precipitation to remove problematic precipitates. The effects of antiscalant type and concentration on salt precipitation and precipitate particle morphology were evaluated for several water compositions. The primary precipitate for the synthetic brackish waters tested was calcium carbonate; the presence of magnesium, sulfate, minor ions, and antiscalant compounds affected the amount of calcium precipitated, as well as the phases of calcium carbonate formed during precipitation. Addition of antiscalant decreased calcium precipitation but increased incorporation of magnesium and sulfate into precipitating calcium carbonate. Antiscalants prevented the growth of nucleated precipitates, resulting in the formation of small (100–200 nm diameter) particles, as well as larger (6–10 μm) particles. Elemental analysis revealed changes in composition and calcium carbonate polymorph with antiscalant addition and antiscalant type. Results indicate that the presence of antiscalants does reduce the extent of calcium precipitation and can worsen subsequent filtration performance.

Impact of Thermal Hydrolysis Solids Pretreatment on Sidestream Treatment Process Selection at the DC Water Blue Plains AWTP

Impact of Thermal Hydrolysis Solids Pretreatment on Sidestream Treatment Process Selection at the DC Water Blue Plains AWTP